The present invention relates to a pressure switch. More particularly, the invention relates to a pressure switch which responds to the weight of a person or object or to a difference in ambient pressure.
There are many situations, industrial, as well as residential, where a switch response to a difference in pressure or gravitational force is essential. Thus, for example, a switch which reacts to the weight of a person or object is a necessary part of many burglar alarm systems, traffic control systems, door opening systems for garages, warehouses, and the like, and so on. Furthermore, there are many industrial, commercial and military situations in which it is necessary to provide an indication or warning of a decrease or an increase in atmospheric pressure, the pressure of a stored gas, or the pressure of a body of water or stored liquid.
U.S. Pat. No. 2,780,693, issued to McClellan on Feb. 5, 1957, discloses a pressure switch having a body of compressible material with conducting sheets of foraminous material at opposite surfaces thereof. Electrically conductive fasteners are provided at spaced points of the body. Each fastener is normally spaced from both the upper and lower conductive sheets, but may extend through either of such sheets. The upper and lower sheets are connected to the electrical conductors so that engagement between one or more of the fasteners with both sheets completes a circuit. The switch has an upper protective sheet of hard and stiff material and a similar lower sheet. The edges of the sheets are spaced about the structure by spacers. If the spacers consist of hard, incompressible material, the upper protective sheet is somewhat flexible, so that under the weight of a wheel of a vehicle, it is moved downward to cause electrical contact between one or more of the fasteners with both electrically conductive sheets. If, alternatively, the spacers consist of compressible material, the upper protective sheet is not essential. The operation of the McClellan switch does not depend solely upon the flexibility of the upper protective sheet, but upon the compressibility and resilience of the body of compressible material between the upper and lower electrically conductive sheets.
The principal object of the invention is to provide a pressure switch which functions efficiently, effectively and reliably to indicate a difference in pressure.
An object of this invention is to provide a pressure switch of simple structure and great durability for indicating a difference in pressure and performing a function in response to such difference.
Another object of the invention is to provide a pressure switch having very few working parts, which parts may be readily standardized, for responding to a difference in pressure efficiently, effectively and reliably.
Still another object of the invention is to provide a mat switch of simple structure which reacts efficiently, effectively and reliably to pressure exerted by a person or object on such mat.
Yet another object of the invention is to provide a mat switch of simple structure, having very few parts, which is inexpensive in manufacture, and reliably responds to the weight of a person or object thereon.
Another object of the invention is to provide a depth switch of simple structure which reacts efficiently, effectively and reliably to an increase in ambient pressure thereon and is especially suitable for determining the submersion of a submarine vessel to a depth beyond a predetermined depth and the storage of a predetermined magnitude of gas or liquid.
Still another object of the invention is to provide a depth switch of simple structure, having very few parts, which is inexpensive in manufacture, and reliably responds to an increase in pressure thereon beyond a predetermined point.
Yet another object of the invention is to provide a barometric switch of simple structure which reacts efficiently, effectively and reliably to a decrease in ambient pressure thereon and is especially suitable for determining the altitude of an aircraft higher than a predetermined point, altitude in general, and imminent change in weather conditions and the decrease in volume of a stored gas or liquid to a level less than a predetermined one.
Another object of the invention is to provide a barometric switch of simple structure, having very few parts, which is inexpensive in manufacture, and reliably responds to a decrease in pressure thereon beyond a predetermined point.
The mat switch of the invention is placed at any desired location and may be hidden under a carpet, in entry areas, hallways, stairways, or other passages, and may be placed in any area desired to be protected without the knowledge of an intruder, or traversed by people or vehicles in order to provide a desired function such as, for example, the opening of a door. The mat switch may be used to actuate an alarm, buzzer, light, or the like, open and close a door, and so on, to warn of the presence of a person or object.
The depth switch of the invention may be made of any desired thickness, shape or size and may be made wafer thin and indicates a difference in liquid depth pressure, stored liquid or gas pressure, or the like. The depth switch may be used to open or close a pressure regulating, or other type of, valve, and to actuate an alarm, buzzer, light, or the like, to warn of too great a pressure.
The barometric switch of the invention may be of any desired thickness, shape or size, and may be made wafer thin. The barometric switch may be used to operate a fan, open or close a louver, vent, shutter, or the like, to protect a structure from an approaching storm, to open vents in a greenhouse when the weather is fair, and to actuate an alarm, buzzer, light, or the like, to warn of the approach of bad weather.